Produced water is a term used to describe water that is produced along with oil and gas during extraction. For example, typical oil and/or gas reservoirs may have a natural water layer (formation water) that lies under hydrocarbon deposits. Extraction of these hydrocarbons can inevitably result in the extraction of produced water. Produced water may also be generated through injection extraction methods known within the industry. In this method, water is injected back into the hydrocarbon reservoir, usually to increase pressure and thereby stimulate production. Both the formation water and the injected water are eventually produced along with the oil. It should be noted that the produced water or compromised water from oil and gas facilities may vary by region or even lifecycle of the well. In addition, produced or compromised water from disparate regions of facilities may be mixed together prior to treatment or disposal resulting in great variation of constituents present in the water. Such variability compounds the need for a solution, such as the current invention that may operate with a wide variability of produced or compromised water constituents. However, while the extracted hydrocarbons are eventually separated from the produced water and further refined for commercial uses, the generation and treatment of produced water raises important technical, environmental, may be economical problems associated with oil and gas production.
For example, produced water may be fresh or salty (or saline) water, but can also contain varying amounts of: hydrocarbons such as oil and grease; industrial chemical additives; sulfides such as hydrogen sulfide; BTEX's (benzene, toluene, ethyl benzene, and xylene-volatile aromatic compounds); other toxic compounds; naturally occurring radioactive material; and sediments. Produced water is usually considered hazardous waste and usually requires special disposal and handling.
Produced water can even represent the largest waste stream associated with oil and gas production. In the United States, it is estimated that on average nine barrels of water are produced for each barrel of oil. The environmental impact of handling, treating and disposing of the produced water negatively affects the profitability of oil and gas production. For example, approximately 60% of water produced with conventional oil and gas is disposed of via deep well injection at a cost of $0.50 to $1.75/bbl in wells that cost in excess of $400,000 to $3,000,000 to create and use. The annual cost of disposing of the produced water in the United States is estimated to be $5-10 billion dollars per year.
Any remaining produced water usually must be treated before it can be released to the environment. Typically, produced water treatment technologies are limited to treating specific constituent types concentrated in the water, e.g., dissolved solids, organics, conductive ions, etc. Depending on the eventual use of the water and the desired constituent concentrations, treatment processes are often coupled together to achieve required water use objectives. However, typical treatment steps are expensive and may be cost/technologically prohibitive depending on a variety of factors such as access to fresh water or other regulatory concerns. For example, the quality of produced water varies from region to region, and some treatment technologies may be viable in one region but not in another region. In addition, operators often produce large volumes of produced water, particularly during the early extraction phase and the quality, as well as the volume may change during the approximately 20 years of life of a well. As such, the ability to treat effectively—and economically—produced water is an important factor in the exploration and formation of new wells. Furthermore, with the advent of new injection well, as well as “hydraulic fracturing” techniques, such concerns have only grown in recent years and will continue to do so for the foreseeable future.
The foregoing problems regarding the treatment of produced water may represent a long-felt need for an effective—and economical—solution to the same. It is well known within the industry that the presence of various chemical such as sulfides and BTEX's are toxic to algae and act as inhibitors to any growth in produced water. In this regard, the Applicant's system for an algae-based treatment of produced water in its various embodiments is contrary to some expectations and effectively solves many of the aforementioned problems in a new and non-obvious way. By providing a cost-effective and commercially scalable method to treat produced or other compromised water (the terms being interchangeable) which may be released or reused for injection extraction techniques, Applicants have solved a particularly vexing problem that has at times been met with astonishment and even disbelief. It should be noted that the Applicant's system also contemplates the production of algal biomass and early bio-fuel feed-stock components as well as the capture and sequestration of carbon-dioxide and other compounds generated from the extraction of hydrocarbons allowing for value-added processes further enhancing the invention's utility and economic viability.
As to embodiments of the inventive technology that relate to techniques, systems, methods and apparatus for the growth of algae to capture and store atmospheric and industrial generated carbon dioxide (CO2) and the like, as background it should be noted at the outset that the earth's atmosphere was created by and is regulated by micro organisms such as algae and bacteria. Originally life on earth evolved as sulfur eating bacteria that fed off hydrogen sulfide expelled from volcanic activity. As the bacteria increased in population, competition for available hydrogen caused a mutation that allowed the new organism to feed on hydrogen contained in water. The process known as photosynthesis uses sun energy to split water molecules and recombine the hydrogen with CO2 that is a hydrated carbon termed a carbohydrate. The byproduct of this reaction is oxygen that is released into the environment. Due to the vast volume of water on earth the water splitting organisms, cyanobacteria and algae, flourished and created an atmosphere rich in oxygen. Oxygen is a highly toxic substance and very reactive with matter. This had the effect of driving anaerobic bacteria into hiding and gave way to a planet rich in plant life.
A second major evolutionary event occurred that allowed bacteria to metabolize plant matter to derive energy is known as oxidation-reduction. It is hypothesized that oxidizing bacteria became incorporated into cells in a symbiotic relationship and co-evolved in animal cells as mitochondria. Mitochondria may utilize oxygen to oxidize carbohydrates with one byproduct being CO2 that is expelled into the atmosphere. For billions of years the earth's atmosphere was generally regulated by the planets inhabitants in this manner. As the planet warmed due to animal produced methane and CO2, i.e., greenhouse gas, levels rising, terrestrial plants and oceanic algae would bloom. As carbon was captured by plants and algae, GHG levels would decrease and planetary temperatures would fall. The variance in atmospheric oxygen, 20.8%, and CO2 ˜1% remained relatively stable as the planets microorganisms, working in a grand symphony, adjusted for changes in the sun's temperature to maintain life in the balance.
As organisms die and sink to the bottom of the seas carbon is pulled out of the atmosphere and stored in organic matter in the earth. Over millions of years this organic matter is converted into hydrocarbons, high in energy. Man has developed the current civilization and populations of seven billion individuals through the utilization of this stored carbon to fuel our lifestyle. However, an unintended consequence of this extraction and combustion of stored carbon is the release of CO2 into the atmosphere, upsetting the balance that the planet's microorganisms have established. For example, CO2 is absorbed by the ocean leading to ocean acidification causing coral reef and shell fish decimation. This has lead in recent years to unprecedented rises in GHG causing global warming, climate instability and associated weather patterns that now are beginning to threaten the established ecosystems on earth as evidenced by rapidly melting polar ice and decimating coral reefs around the world.
It is estimated that direct carbon combustion for energy production generates more than 24 gigatons of CO2 annually. As a result, atmospheric CO2 concentrations have risen from approximately 295 parts per million (ppm) to 380 ppm over the last 100 years, and have contributed substantially to global warming, climate change, and resultant biological extinctions.
The geo-political reality is that mankind will continue to extract and burn carbon in the form of oil, gas, coal and wood for as long as it lasts. This process is accelerating as new technologies are developed to more efficiently and economically utilize fossil fuel. Also, as deposits of fossil fuels decrease, competition for the remaining reserves increases. For this reason the strategic petroleum reserve (SPR) was created in the United States following the OPEC oil embargo in the seventies as a buffer against interruption of oil supplies in the US. The SPR consists of some billions of barrels of oil stored in salt formations in several sites in America. When needed they can be drawn down and theoretically replenished when the emergency passes. The theoretical capacity of the SPR is 36 days, although in reality it would take 160+ days to actually pump, refine and deliver the stored petroleum to the market. In recognition of the finite supply of fossil fuels, which may take millions of years to develop under natural conditions, the US Government has embarked on a plan to replace traditional oil and gas with biofuels. Legislation has been passed in recent years establishing the renewable fuels standard, which mandates percentages of our transportation fuel comes from biofuels. Biofuels may be produced from organic matter in a very short time span, which is in a matter of days rather than years. Early biofuels feed stocks may include corn and soybean oil. Advanced biofuels feedstocks under development may be derived from algae and cellulosic matter. However, a major problem with biofuels production is the gap between GHG production and commercial profitability. Current technology may utilize cheap energy derived from fossil fuels to cultivate, harvest, extract and convert biomass into fungible (drop in) fuel replacements. Efficiencies are not yet available to produce high energy dense liquid fuels to replace gasoline and diesel use economically.
The purpose of this methodology may be two-fold. First, it may be desirable to capture GHG rather than continue to emit them to the atmosphere in order to reduce carbon levels in the atmosphere and reduce planetary temperatures. Secondly, it may be desirable to increase strategic petroleum reserves.
While implementing elements may have been available, actual attempts to meet this need may have been lacking to some degree. This may have been due to a failure of those having ordinary skill in the art to fully appreciate or understand the nature of the problems and challenges involved. As a result of this lack of understanding, attempts to meet these long-felt needs may have failed to effectively solve one or more of the problems or challenges here identified. These attempts may even have led away from the technical directions taken by the present inventive technology and may even result in the achievements of the present inventive technology being considered to some degree an unexpected result of the approach taken by some in the field.